In the figure, an object is placed at distance `25 cm` from the surface of a convex mirror, and a plane mirror is set so that image formed by the two mirrors lie adjacent to each other in the same plane. The plane mirror is placed at `20 cm` from the object. What is the radius of curvature of the convex mirror ?
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Answer

R = 75 cm

Explanation

Image due to plane mirror will form at a distance of `20 cm` left of the mirror.
Since image formed by two mirrors lie adjacent to each other.
For convex mirror, image position is `15 cm` towards left
`u=-25 cm rArr v=+15 cm`
using `(1)/(v)+(1)/(u)=(1)/(f)=(2)/(R)`
`(1)/(15)-(1)/(25)=(2)/(R) R =75 cm`.